Monthly Archives: July 2010

Extracting Raster Values from Points in R and GRASS

July 26, 2010
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A common task in GIS analysis is to extract the value of a remotely sensed environmental variable at a point location. For instance we may wish to extract the elevation of a field plot from a digital elevation model. The elevation data is a raster (i.e. grid) and the plots are a point shapefile (or a simple text file of X,...

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Extracting Raster Values from Points in R and GRASS

July 26, 2010
By

A common task in GIS analysis is to extract the value of a remotely sensed environmental variable at a point location. For instance we may wish to extract the elevation of a field plot from a digital elevation model. The elevation data is a raster (i.e. grid) and the plots are a point shapefile (or a simple text file of X,...

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Richard Stallman talk+Q&A at the useR! 2010 conference (audio files attached)

July 26, 2010
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The audio files of the full talk by Richard Stallman are attached to the end of this post. —————– Videos of all the invited talks of the useR! 2010 conference can be viewed on the R User Group blog —————– Last week I had the honor of attending the talk given by Richard Stallman, the last keynote speaker on...

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Using SAS for Data Management, Statistical Analysis, and Graphics

July 26, 2010
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Using SAS for Data Management, Statistical Analysis, and Graphics

Our newest book, Using SAS for Data Management, Statistical Analysis and Graphics, will soon be shipping from Amazon, CRC Press, and other fine retailers. The book complements our SAS and R book, particularly for users less interested in R. It presen...

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New R User Group in Melbourne

July 26, 2010
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Data mining analyst Yuval Marom has just started a new user group for users of R in Melbourne (the one in Australia). He says: The group is open to people with all levels of experience with R, including complete beginners and complete experts, and people from all industries - private, government, and academic. The main purpose of the group...

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R Plotting tips

July 26, 2010
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Yes...I haven't been updating the blog for a very long while...But I'm really busy with many things right know.... Our paper for the "Cultural Evolution in Spatially Structured Populations" have been accepted so we are currently working on that, and I ...

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R Plotting tips

July 26, 2010
By

Yes...I haven't been updating the blog for a very long while...But I'm really busy with many things right know.... Our paper for the "Cultural Evolution in Spatially Structured Populations" have been accepted so we are currently working on that, and I ...

Read more »

Circle packing with R

July 26, 2010
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Circle packing with R

To visualize the results of a simulation model of woodland trees within R, I needed an algorithm that could arrange a large number of circles within a rectangle such that no two circles overlapped by more than a specified amount. A colleague had approached this problem earlier by sorting the circles in order of descending size, then randomly dropping...

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Circle packing with R

July 26, 2010
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Circle packing with R

To visualize the results of a simulation model of woodland trees within R, I needed an algorithm that could arrange a large number of circles within a rectangle such that no two circles overlapped by more than a specified amount. A colleague had approa...

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Asher’s enigma

July 25, 2010
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Asher’s enigma

On his Probability and statistics blog, Matt Asher put a funny question (with my rephrasing): Take a unit square. Now pick two spots at random along the perimeter, uniformly. For each of these two locations, pick another random point from one of the three other sides of the square and draw the segment. What is

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